If an e-mail clients blocks images by default, such as Outlook 2003, a recipient can read an entire message either in the message preview pane or when it's opened, but no images will be shown and neither will the message be counted as opened.
The Blocked Images Issue
It has been estimated that 95 percent of all commercial e-mail messages are sent in HTML or in multipart format. Most e-mail includes at least a single external image, even if it's the open-tracking image (a clear, one-pixel GIF image used to track whether an e-mail has been opened.)
External images include logos, mastheads, and product or people photos. Virtually all e-mail marketers host images on a Web server, rather than embed them within the message itself. To load images, a call is made back to the hosting server. The trend is ISPs and some e-mail clients have started to block this call.
The primary reason behind image-blocking is to prevent spammers from knowing if users open their messages. Gmail, for example, states: "Gmail disables images sent to you to protect you from unknown senders, like spammers, who use images and links to verify that your email address is real."
The latest versions of many major ISPs' e-mail interfaces and e-mail clients automatically block any external image. Microsoft's recent Windows XP Service Pack 2 upgrade adds the blocked images feature to its Outlook Express client.
Implications for Permission Marketers
* Lower open rates. More recipients scan e-mail in the preview pane or open messages with images disabled.
* Disabled banner ads. For ad-supported newsletters, disabled images means hosted ad formats aren't displayed. Advertisers may see fewer impressions and click-throughs.
* Many e-commerce-oriented marketers who use aggressive promotional copy repeatedly throughout their messages have significant problems with content-based filters. To overcome this, some place much of their copy within images to avoid being filtered. This could increase delivery rates but result in fewer recipients actually seeing the copy.
What Can Marketers Do?
* Get whitelisted. Some ISPs (notably AOL) and most managed mail networks can whitelist commercial mailers. This ensures selected e-mail is allowed through with a minimum of filtering...image blocking included.
* Add a "view Web version" link. Host a version of your message on the Web. Provide a text link to it at the very top of your message.
* Create text versions. With HTML e-mail so popular, text versions tend to be neglected. Yet recent e-mail client changes mean users have an increased ability to select which default format they prefer. A strong text version ensures you still reach users, regardless of format preference.
* Include more text links. If your e-mail includes several key linked images, consider adding text-based links above or below the image or appropriately placed in nearby copy.
* Focus on CTRs and conversion rates. Don't obsess over open rates.
Blocked images should only be a minor nuisance for most permission e-mail marketers who provide real value to recipients. Follow the above tips and continue to deliver the best, most relevant content to subscriber.